Fungal Infections Part 2

Question 1

What are opportunistic molds?

Answer 1

they are ubiquitous. They are commonly found in the environment, air, soil and decaying matter. reproductive spores are routinely inhaled. they cause opportunistic infections.

Question 2

Opportunistic molds are slow/fast growers?

Answer 2

fast. they can develop colonies in 3-5 days.

Question 3

What is one of the most common opportunistic molds?

Answer 3

aspergillus species. (aspergillus fumigatus is one of the most commonly isolated species.

Question 4

What is the allergic response to aspergillus?

Answer 4

allergic response to antigens: asthma, elevated IgE, eosinophilia

Question 5

What is the upper resp. symptoms to aspergillus?

Answer 5

discharge, HA, facial pain

Question 6

What is the obstructive bronchial aspergillosis and aspergilloma syndrome? (fungus ball)

Answer 6

bronchi become obstructed with mold. usually asymptomatic, and causes no additional symptoms. not treated.

Question 7

Aspergillus can cause serious problems in those who are immunosuppressed, what are the problems?

Answer 7

can cause disseminated disease, usually WBC is below 500. Often involves lung, and can cause suffocation in the patient. Can also spread to brain, heart kidneys, GI, liver, and spleen. Prevention is filtering home air.

Question 8

What is the stain to use for aspergillus sp fungal infections?

Answer 8

gomori methanamine silver stain (silver stain). will show dichotomous branching. Or you can use a calcoflour white stain (fluorescent stain).

Question 9

How long will a fungal culture for aspergillus take to grow?

Answer 9

2-4 days. then confirmed by 7 days. can grow on routine bacterial media.

Question 10

Is every aspergillus infection that grows on culture worth treating?

Answer 10

It depends. Factor in patient symptoms to decide if treatment is necessary. Not always needed.

Question 11

What is the treatment for aspergillus?

Answer 11

surgery to remove if possible or antifungals: voriconazole and amphotericin B/

Question 12

What is a dimorphic mold? What are two examples?

Answer 12

exhibits two morphological forms.
35 degrees = yeast phase (parastic phase)
22 degrees = mold phase (saprobic phase)

examples = histoplasma capsulatum and coccidiodes immitis.
They are inhaled and then disseminate to the lymph system and reticuloendothelial system.

Question 13

Describe histoplasma capsulatum?

Answer 13

endemic to midwest, associated with bird and bat droppings. most cases are asymptomatic. The disease tends to progress in : children, immunocompromised, and lung disease. It can be reactivated in those who are immunocomprised (ex. Aids)

Question 14

Are are the three infection states of histoplasma capsulatum?

Answer 14

Acute, Chronic and Systemic

Question 15

Describe Acute histoplasma capsulatum

Answer 15

similar to TB: fever, weight loss, lymphadenopathy. self-limiting.

Question 16

describe chronic histoplasma capsulatum

Answer 16

calcified nodes, chronic cavitary disease, granulomas

Question 17

describe systemic histoplasma capsulatum

Answer 17

fever, weight loss, hepatomegaly, spleenomegaly, lymphadenopathy

Question 18

How do you detect histoplasma capsulatum?

Answer 18

1) antigen detection in serum, urine, and CSF: sensitive to systemic disease and therapy monitoring.
2) Antibody detection: IgM= acute, IgG= current or chronic. >75% in endemic areas (IgG)
3) Fungal stains are not very useful. detect fungal stage
4) Fungal culture: chronic and systemic. Takes 1-3 weeks.

Question 19

What is the treatment for histoplasma capsulatum

Answer 19

mild to moderate: itranconazole for at least 12 months
Severe: amphotericin B for 2 weeks, then itranconazole for 12 months. Consider prophylaxis for HIV patients with CD4 < 150.

Question 20

Describe coccidiodes immitis

Answer 20

endemic to the desert southwestern US. Those who are at risk include >65 years, immunosuppressed, pregnancy, ethnic: filipino, african american, native american, hispanic, asian. The disease state and progression is similar to histoplasmosis. IgG provides life long immunity.

Question 21

Does IgG antibody provide lifelong immunity for coccidiodes immitis?

Answer 21

yes

Question 22

What does antibody detection for coccidiodes immitis tell you?

Answer 22

IgM= acute infection
IgG= chronic
If found in CSF= meningitis.

Question 23

What will a fungal stain of coccidiodes immitis show?

Answer 23

endosporulating spherule

Question 24

what will a fungal culture of coccidiodes immitis show?

Answer 24

growth takes around 2-4 days. useful for chronic and systemic disease.

Question 25

what is systemic dimorphic serology cross-reactivity?

Answer 25

looking for patient antibody to a specific fungal infection. There is cross-reactivity between systemic dimorphic organisms.

Question 26

Will a patient with a true coccidiodes immitis infection also test positive for Histoplasma.

Answer 26

yes, due to cross reactivity